The Trump administration’s policies are making life more complicated for US diplomats abroad.

In the past few days, senior US diplomats in two friendly countries – France and Denmark – have been summoned to receive diplomatic protests from the host government. This is unusual.

Denmark has called in the US charge d’affaires (as the ambassador has not yet been confirmed) after intelligence reports suggested there were covert efforts by the US in Greenland to stir up opposition to Danish rule.

And in Paris, the new US ambassador, Charles Kushner, was summoned after publicly criticising the Macron government for not doing more to curb anti-semitism – but sent one of his staff instead.

Trump’s approach to diplomatic relations dispenses with the usual niceties, the traditional courtesies, and cuts to the chase: who’s bigger than who? The suggestion is that if it is Trump, then he expects you to do what he wants. Where a foreign government continues to disagree with his policy, he seems willing to support efforts, as in Greenland, to change the government or publicly pressure them to change.

US president Theodore Roosevelt (1901-1909) advised his successors to speak softly and carry a big stick. Trump clearly prefers to speak loudly and use the stick liberally, especially on the country’s allies. This is a new US diplomatic game.

All of this prompts the questions: what is the proper role for an ambassador abroad, and how should diplomatic relations be conducted? As I have set out in my recent book How to be a Diplomat – drawing on 35 years as a British diplomat working in Africa, the Middle East, the US and the EU – there are rules, customs and practices, but these are not always observed.

The Vienna Convention of 1961, which sought to codify this practice, made clear that ambassadors should be respected as representatives of another sovereign state through the granting of appropriate diplomatic privileges and immunities. But that in turn, they should respect the host government by not criticising it in public or seeking to interfere directly in its internal affairs.

The role of the ambassador

Ambassadors act as a mouthpiece for their government, and it is common for governments not to agree with each other. Ambassadors are there to represent, but also to explain, persuade and negotiate on points of difference.

For that, you need to be able to talk to the host government. Insulting them in public, as Kushner did through his op-ed in a US newspaper, does not encourage dialogue or lead to fruitful outcomes.

There are well-established ways to manage such differences. Formal protests from one government to another are usually communicated through a diplomatic communication known as a note verbale using a formal course of action called a démarche – delivered either by an ambassador to the host government, or by summoning the ambassador of the country concerned to the foreign ministry to meet the foreign minister or most senior official.

Ambassadors can be summoned too over the misbehaviour of their staff or citizens in the country concerned, or to expel some of their staff for undertaking activities incompatible with their status – the customary circumlocution for spying.

If relations deteriorate further, an ambassador can be declared persona non grata, effectively expelled, or formally “withdrawn for consultations”, though a charge d’affaires will often remain to ensure a means of communication between the governments continues.

While British ambassador to the Ivory Coast, I was PNG’d by President Laurent Gbagbo after I had, together with the rest of the diplomatic corps in Abidjan, asked him to respect the result of the 2010 election and stand down. (In the end, he went before I did.)

The ultimate diplomatic sanction – usually the last step before war is declared – is to break off diplomatic relations entirely, withdraw all staff, and close the embassy.

When US vice-president J.D. Vance visited Greenland in March 2025, he criticised Denmark’s governance of the territory.

In Trump’s first administration, his ambassador to Germany, Richard Grenell, ruffled feathers with implied support for the far-right in Europe, including the AfD, and criticism of Angela Merkel’s chancellorship.

An infuriated German government had as little contact with him as possible after that, though he was never actually expelled. The same fate is likely to befall Kushner in France: he may become politically popular in Washington and Tel Aviv, but could become operationally useless in France.

Trump, however, has not hesitated to dish it out to foreign ambassadors at home as well as governments abroad. In 2019, he effectively forced out the British ambassador to Washington, Kim Darroch, by refusing to meet him after some mildly critical comments in a classified internal report were leaked to the British press. When then-foreign secretary Boris Johnson refused to back Darroch up, he had no option but to resign.

Foreign affairs

During the cold war, both the US and Soviet governments were, on occasion, actively involved in trying to install more sympathetic governments in third countries – most memorably in Iran in 1953, Czechoslovakia 1968 and Chile in 1973. But ambassadors were usually left out of the action, which was undertaken by other agencies.

The question is whether this US administration’s approach constitutes a re-writing of the diplomatic rules, or just a return to the status quo before 1945. At that point, the world decided through the UN to try to bring more order and rules to international relations, rather than allowing the great power free-for-all which had led to two world wars.

In reality, the balance of power has always underpinned diplomacy. But even great powers (the biggest nations) came to realise that some rules were useful, which is why the UN still exists.

Diplomacy will continue come what may. And the jury is still out on whether Trumpian realpolitik will actually deliver better outcomes for American people than the previous way of working he is trying to ditch.

This article is republished from The Conversation, a nonprofit, independent news organization bringing you facts and trustworthy analysis to help you make sense of our complex world. It was written by: Nicholas Westcott, SOAS, University of London

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Nicholas Westcott does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.